Burning pulverized fuel.



H.BARNHURST,DEUD.

II. G. BAIINIIIIRST, ADMINISTRATOR. BURNING PULVEHIZED FUEL. APPLICATION FILED MAI'I. sI. I9I4.

Patented Apr. 4, 1916.

UNITED STATES PATENT' OFFICE.

'HENRY G'. BARNHUBST, ADMI'NISTRATOR,

0F CATASAUQUA, PENNSYLVANIA,

BURNING PULVERIZED FUEL.

Specification of Letters Patent.

Application filed March 31, 1914. Serial No. 828,465.

To all whom it may concern.'

Be it known that HENRY R. BARNiiURs'r, deceased, late a citizen of the United States, residing at Third and Pine streets, Catasauqua, Lehigh county, State of Pennsylvania, has invented certainnew and useful Improvements in Burning lulverized Fuel; and l, HENRY (l. BARNHURs'r, administrator of the estate of the said HENRY R. BARN- HURs'r. do hereby declare the following to be a full, clear, and exact description of the invention, such as willenable others skilled in the art to which it appertains to make and use the same.

The invention relates to certain new and useful improvements in the burning of pulverized fuel, and has particular relation to the method of establishing and maintaining the necessary conditions for effective combustion for obtaining predetermined temperatures suitable for given conditions of use.

lt also lrelates to the construction and arrangement of the means of apparatus 'for practising the method.

In carrying out the invention there is located within the interior of the pipe or con'- duit which is to deliver into the furnace chamber the combustible mixture of air and pulverized fuel, a pipe of relatively smaller diameter, which conveys and discharges intoy the outer pipe a current of air of high pres sure which it receives from any suitable source of supply. The interior high pressure'air pipe referred to discharges into the outer pipe ata point sufficiently removed from the discharge end of the outer pipe to permit the high pressure air to exercisean effective propelling effect upon the mixture of air and pulverized fuel on its way to the furnace chamber andto keep the pulverized fuel in suspension in the air mixture. To render the operation effective, the high pressure air jet discharged from the inner tube is utilized for two auxiliary and cooperating purposes, to wit,-to draw in air with the pulverized fuel as the latter is fed into the outer pipe, and to draw in air through the longitudinal annular space existing between the inner and outer pipes. Accordingly. the air provided for the consumption of the fuel is admitted at three different sources of supply, that is to Say. l l) through the annular space between the outer `pipe and lthe inner high pressure pipe, (2) through the high pressure pipeitself; and (3) through the opening which admits the pulverized fuel, said opening being in close proximity to the discharge end of the high pressure pipe, so that the entering fuel with its entrained supply ofl air will be promptlyT forwarded by the injecting action of the high pressure jet into the main body portion of the outer pipe. Just before entering the rone in advance of the discharge end of the high pressure jet, the mixture of air and fuel drawn in through the fuel opening will be joined by thevolume of air drawn in through the annular space between the inner and outer pipes. and, finally, as

hereinbefore` indicated, the resultant air and fuel mixture will be further augmented by the supply from the high pressure jet itself, whose propelling effect will be exercised in assuring regular, sustained and uniform delivery of the ultimate mixture from the discharge end of the outer pipe into the furnace chamber or other combustion space intended.

The fuel travel provided in the practice of the invention is quite short after the delivery of the fuel and its associate air into the. burner pipe, and the mixture of air and fuel should enter the combustion chamber at a relatively low pressure and a relatively low velocity. Consequently, this low pressure and velocity, with respect to high pressure of the central air injecting jet should prevail in the space intervening between the discharge end of the high pressure jet and Athe discharge end of the outer pipe, While,

at the same time, the conditions should be such that the pulverized fuel is sustained Patented Apr. 4, 191e.

in the air current without danger of de-y positing in the'pipe. These functions are attained in the practice of the invention by locity and energy'of the primary air jet for imparting a lower velocity and pressure to the secondary air delivery` with the resultant effect that 'a largely increased vol ume of total air of the appropriate low velocity and pressure,y and having disseminated through it ay practically homogeneous burden of pulverized fuel will be discharged into thel furnace chamber.

lt is. of course, important. and indeed essential, that the volume of air associated making available the relatively high ve-l with the fuel vand passing out of the burner pipe in admixture with it, shall be capable of close control, inasmuch as the maintenance of proper temperatures within the furnace chamber isdependent upon the proportion by volume which the air bears to the fuel. `ln the present invention, provision is made for accuratelyregulating the supply of air entrained between the inner and outer pipes, by means of a regulating cone which may conveniently be sleeved upon the inner pipe and which is capable of longitudinal adjustment so as to vary the effective' area of entrance of the secondary air at the air admission end ofthe outer pipe. By this expedient, the volume of secondary air thus admitted may be controlled with great precision, and without cutting down the pressure of the injector jet, which pressure should remain practically constant in its relation to the entrainment of the air and fuel through the fuel supply opening. lt is further characteristic of the invention that it dispenses with the necessity for the employment of fans or blowers for supplying the secondary air to the burner, and that there is no constriction or obstructionin the annular space through which the secondary air supply passes.

ln the accompanying drawing- Figure l represents a longitudinal sectional view, of a pulverized fuel burner embodying the invention; l? ig. 2 represents a top plan view thereof, partly in section; and Fig. 3 represents a cross-section on the line 3-3 of Similar numerals of reference indicate similar parts throughout the several views.

Referring to the drawing, 30 indicates the outer tube or burner pipe, preferably of substantially oval cross-section, as indicated in Fig. 3. 'lhe burner pipe 30 may be provided with any suitable mouth piece, as 38, to direct or distribute the discharge, and the directing mouth piece, if desired, may be water-cooled at 39 andll-O, as shown. rl`he burner pipe 30 is entirely open at its rear end, and receives an inner high pressure air injector pipe 32, separated. therefrom by an intervening annular space and which is supplied with air from any suitable source, as, for instance, from a fan operating to supply the air at constant pressure and velocity. Slidably mounted on the air injector pipe 32 is a cone 37, which may be advanced toward or retracted from the rear open end of the burner pipe 30 to regulate the effective area of the opening between the burner pipe the air injector pipe. Pipe 32 is provided with a suitable damper or regulator 32.

The burner pipe 39 has a fuel receiving funnel 31, above which is supported a nozzle 29, through which the pulverized fuel is dropped into the burner -pipe 30, in near 'nin-ieee proximity to the discharge end of the inner pipe 32. The pulverized fuel, as, for instance, pulverized bituminous coal, is supplied to the nozzle 29 by feed apparatus, of such a' character that the partial .vacuum due to the intake of air at the funnel 31 shall not accelerate the feed and thus interfere with its regularity and uniformity. llfhus the feed apparatus may conveniently consists of a hopper 15 from which the dry pulver-ized coal passes through a pair of adjustable gates 1S and 17 into a housing 19 wherein a screw conveyer 19 is suitably mounted. rfhe shaft .20 of the screw conveyer is carried at its rear end in a bearing 21, and is equipped with a sprocket wheel :22, whereby it may be driven to advance the pulverized fuel admitted from the hopper 15. fit the front end of the housing 18, and preferably removable therefrom for purposes of repair, is an auxiliary housing 23 at the end of which is a removable front bearing '2l-l, wherein the shaft of the screw conveyer is journaled. ein auxiliary conveyer 25 is mounted on this shaft, but is spaced from the front end of the conveyer 19 far enough to form a substantial gap 26. The blades of the conveyers 19 and Q5 may be made integral with the shaft 29 or may be suitably attached thereto, and they preferably fit closely within the housing with the minimum practicable amount of clearance.

ln operation, the pulverized coal is carried forward by the screw flights or convolutions of the conveyer 19 until it reaches the gap 2G. Not being propelled forward by the convolutions at this point, the material accumulates in the gap, but, as further material continues to be delivered by the conveyer 19, the material in the gap, receiving constant accretions, is pushed bodily forward upon the convolutions of the conveyor 25, which thereupon takes up the delivery of material at the same rate at which it has been built up in the gap by the convolutions of the co-nveyer 19. lhe material within the gap constitutes, therefore, a dani against tendency to fiood, that is to say, to accelerate the motion of the pulver-ized fuel in the conveyer housing.

il] hen the blower is in action, delivering air at high velocity through the pipe 82 into the burner pipe 30, there will be developed by the injector action an inflow of air through the funnel 31, so that the pulverized fuel dropping through the fuel noz- Zle :29 will be caught by this downwardly moving air and mixed therewith. So also, secondary air will be entrained through the rear open end of the burner pipe 30, the proportional amount depending upon the adjustment of the movable cone 37, and upon the velocity and constancy of pressure of the air supplied by the pipe 32. its the result of these several factors, the high-velocity air supplied by the pipe 32 becomes mixed .with a larger volume of air drawn in through the rear of the pipe 30 and also velocity and so is scattered across the entire 4 cross-section of the tube, and is started toward the burner nozzle at a speed sufficient to obviateany danger of deposit of the fuel in the burner pipe. But, when the mixture ofair and fuel reaches the-burner nozzle, said fuel and the high-velocity air which gives it impetus have become so intimately mixed with the much larger volume of entrained air thatvthe whole mixture issues from the burner nozzle at the desired low velocity. This permits the fuel tov burn close to its point of admission so that the surrounding wall receives the heat desirable for maintaining its prompt defagration as it enters the furnace chamber.

By the arramgement` disclosed it is possible to use a small high pressure fan and yet obtain at the delivery ends of the burner pipe a large volume of low pressure air within which the pulverized fuel is properly distributed; and, by suitably adjusting the sizes of the air supply pipe 32 and the burner pipe 30, it is possible to obtain at the burner nozzle the appropriate low ve-.,

locity and the appropriate ratio between the pulverized fuel and the total air to correspond to the particular exigencies of use. The. definite provision thus afforded for predetermining the character and velocity of thc entering con'ibustible mixture, enables the operator to produce a given temperature within the'furnace by'correspondingly calibrating the amount and rate of fuel supply to the known velocity and )ressure of the air which passes through the pipe 32, and the amount of the secondary air entering at the rear open end of the pipe 30 and regulated by the position to which the cone is adjusted.

It will be noted, as a further advantage of the construction, that the feature of feeding the pulverized fuel from-the nozzle 29 through the funnel-shaped opening 31 permits the operator to observe the flow of the pulverized fuel as it issues from the nozzle, and the character of the feed, so that he can at all times determine whether it is proceeding with the required uniformity and regularity.

'hat is claimed is:

l. Ajiparatus for burning pulverized fuel, comprising au outer burner pipe, open at its ends, an inner high pressure air injector pipe projecting thereinto with an annular space therebetween, means for regulating the flow of air through said inner pipe, said inner pipe serving to entrain a secondary supply of dair through said annular space,l means for regulating said secondary supply of air, the outer pipe being provided with an inlet opening, rearwardly of the discharge end of the injector pipe, and means for dropping pulverized fuel through said inlet opening; substantially as described.

2. Apparatus for burning pulverized fuel,

comprising an'outer burner pipe, open at its ends, an inner high pressure air injector` pipe projecting thereinto with an annular space therebetween, said inner pipe ser-ving to entrain a secondarysupply of air through said annular space, the outer pipe being provided with an inlet opening, rearwardly of the discharge end of the injector pipe, means for dropping pulverized fuel through said inlet opening, and a regulating cone for varying the effective area of the annular space between the two pipes; substantially as described.I

3. Apparatus for burning pulverized fuel, comprising an outer burner pipe, open at its ends, an inner high pressure air injector pipe projecting thereinto with an annular space therebetween, said inner pipe' serving to entrain a secondary supply of air through vided with lan inlet opening rearwardly of the discharge end of the-injector pipe, said opening` having a short funnel-like rim, and a pulver-ized fuel feed nozzle discharging into saidrimwhile permitting the intake of air through said inlet opening about said nozzle; substantially as described.

4. Apparatus for'burning pulverized fuel, comprisingran outer burner pipe, open at its ends, -an inner high pressure air injector' pipe projecting thereinto with an annular space therebetween, said inner pipe serving to entrain a secondary supply of air through said annular space, the outer pipe being provided wit'h-an inlet opening rearwardly of the front end of said inner pipe, said opening having a funnel-like rim, a pulverized fuel feed nozzle discharging into said rim while permitting the intake of air through said inlet openingabout said nozzle, a conveyer housing-for supplying the pulverized fuel to the nozzle, said housing being open from end to end, and conveyers within'the housing, for forwarding the pulverized fuel to the nozzle, said conv'eycrs being separated by an intervening gap for the formation and maintenance of a fuel dam thereat which will protect the feed from abnormal acceleration in the housing; substantially as described.

5. Apparatus for burning pulverized fuel, comprising an outer burner pipe, open at its ends, an inner high pressure air injector izoA pipe projecting thereinto with an annular space therebetween, 'said inner pipe serving to entrain a secondary supply of air through said annular space, the Outer pipe being provided with an inlet opening and having a shallow*funnel-like rinl, a pulverized fuel feed nozzle discharging into said rim dWhile permittingr the intake of air through said inlet opening about said nozzle, anda regulating Cone mounted on said high pressure air pipe for varying the effective area of the annular space between the two pipes; substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

HENRY Gr. BARNHURST, Ad'nL/m'stmzwof' Hemgz/ R. Barnhurst, Ze-

ceasecl. Vitnesses VICTOR J. Downs, Ro'r. E. GANGAWER. 

